This invention relates to regulated deflection circuits for television receivers, for example.
In typical television receiver circuitry, the horizontal deflection winding and a trace capacitor are series coupled. The trace capacitor is charged to a trace voltage from a B+ voltage supply through a flyback transformer primary winding. A trace switch then couples the trace capacitor to the deflection winding and applies the capacitor voltage across the winding to generate a trace deflection current. During retrace, the trace switch is nonconductive and the deflection winding and flyback transformer primary winding resonate with a retrace capacitor to generate retrace pulse voltages in the two windings.
During retrace, the deflection current reverses in direction preparatory to starting the next deflection interval. The retrace pulse voltage in the flyback transformer primary winding is stepped up by a high voltage winding to generate the high voltage or ultor accelerating potential.
To maintain a constant raster width, the trace voltage developed across the deflection winding and the retrace pulse voltages are regulated. To achieve this result, conventional television receiver regulators, using controllable semiconductor switching elements, develop a regulated B+ supply voltage derived from an unregulated input voltage, such as a voltage derived from the AC line or mains supply. For greater efficiency, such switching elements typically operate at the relatively high frequencies of 16 or 20 kilohertz.
Other television receiver regulators such as described in the U.S. patent application of D. H. Willis, Ser. No. 058,659, filed July 19, 1979, a continuation of Ser. No. 926,337, filed July 20, 1978, now abandoned; both applications being entitled "REGULATED DEFLECTION CIRCUIT WITH REGULATOR SWITCH CONTROLLED BY DEFLECTION CURRENT", couple the unregulated input voltage to the flyback transformer primary winding and to the deflection winding and trace capacitor. A second capacitor is coupled to the trace capacitor and is charged to a voltage which follows the input voltage variations. The trace voltage, established as the difference between the input voltage and the second capacitor voltage, is thereby regulated. The charge-discharge cycle of this second capacitor occurs at the 16 kilohertz frequency of horizontal deflection.
Controllable semiconductor switching elements used in the above-described regulator circuits may be relatively expensive, may be subject to switching failure, and may require relatively complex control circuitry. It is desirable to design a regulator circuit which operates at the higher frequencies of the above-described circuits, but which does not require controllable semiconductor switching elements to perform the regulation.